Java/Json Object Parser

Java/Json object parser is a tiny tool for parsing elements from complex java/json object.

Usage

Annotation

By annotations, you can build a java object from another java/json object.

For example, if you have an object origin, which is a combination of multiple complex objects, and you want to retrieve some fields from this object and construct another object, you can use annotation to accomplish this.

public class TestObj_1 {
    private int a;
    private Long b;
    private TestObject_In in;
    private TestObjComplex_origin data;

}

public class TestObject_In {
   private int c;
}

public class TestObjComplex_origin {
    private int o_a;
    private String o_b;
}

//dest class
public class TestObject_dst {
    @FieldPath("a")
    private int dA;
    @FieldPath("b")
    private long dB;
    @FieldPath("in.c")
    private int dC;
    @ClassFieldPath("data")
    private TestObjComplex_dst data;
}

public class TestObjComplex_dst {
    @FieldPath("o_a")
    private int a;
    @FieldPath("o_b")
    private String b;
}

From above code, you can see that TestObj_1 is a combination of TestObject_In and TestObjComplex_origin and two primitive fields.

And you want to do the following mappings:

• TestObject_dst.dA <--> TestObj_1.a
• TestObject_dst.dB <--> TestObj_1.b
• TestObject_dst.dC <--> TestObj_1.in.c

and then map TestObject_dst.data and TestObj_1.data with following mappings:

• TestObjComplex_dst.a <--> TestObjComplex_origin.o_a
• TestObjComplex_dst.b <--> TestObjComplex_origin.o_b

For primitive fields with same type, just use the FieldPath annotation, and set it's value to the field path.

For compound fields you need to use ClassFieldPath annotation, and set it's value to the filed path.

For list fields you should use ListFieldPath, and you should add element type as another param.

If you want to retrieve an element in list by it's index, just add[index] to the field path.

A field path is the path for looking for the filed you want in the dest class.

Java API

Java API is useful when you want to get a few fields by field paths.

For example, you want to get the value of the second element of the first element in data's objList field, just use JsonObjectParser parse = new JsonObjectParser(json) to construct a parser, then get the value by parser.getInt("data.objList[0].c[1]"). Very easy!

  {
            "data" : {
            	"o":{},
            	"int":1,
            	"true":true,
            	"false":false,
            	"long":100,
            	"double":100.2,
            	"string":"string",
            	"date":1463046784000,
            	"detail":{
            		"a": 11,
            		"b": "dB"
            	},
            	"strList" :[
            		"a","b"
            	],
            	"intList" : [
            		1,2,3
            	],
            	"longList" :[
            		2,3,4
            	],
            	"doubleList" :[
            	   1.1,2.2,3.3
            	],
            	"objList" : [
            	  {"a":1,"b":"bb","c":[1,2,3]},
            	  {"a":2,"b":"bb2"}

            	]
            }
        }

Parsers

• JsonObjectParser: used to parse json object
• ObjectParser: used to parse java object

Have fun!